With the adoption of fine lithographic patterning techniques in semiconductor manufacturing processes, there arises a need to provide resist compositions that can be exposed at shorter wavelengths and show wide depth of focus tolerance (abbreviated as “DOF”), small line edge roughness (abbreviated as “LED”), high resolution, high sensitivity, good substrate adhesion and high etching resistance.
It is reported that the introduction of a fluorine atom or an aliphatic moiety into a resist resin would produce a certain effect on the reduction of the exposure wavelength. Further, it is attempted to use, as an anion moiety of an acid generator, a fluorine-containing sulfonic acid of high acidity in order to attain wide depth of focus tolerance and small pattern line edge roughness. It is also attempted to provide a resist resin whose copolymerization component has an acid generator function for improvements in resist characteristics. As such a resist resin, there have been proposed a resin containing a sulfonic acid onium salt as an acid generator in a side chain thereof with an anion moiety of the acid generator fixed to the resin (see Patent Documents 1 to 7). For example, Patent Documents 6 and 7 disclose resist compositions, each of which uses a resin obtained by polymerization or copolymerization of a methacrylic acid ester containing in a side chain thereof a triphenylsulfonium salt of sulfonic acid having a fluorine atom at its α-position.
[Prior Art Documents]    Patent Document 1: Japanese Patent No. 3613491    Patent Document 2: International Application Publication No. WO 2006/121096    Patent Document 3: Japanese Laid-Open Patent Publication No. 2006-178317    Patent Document 4: Japanese Laid-Open Patent Publication No. 2007-197718    Patent Document 5: Japanese Laid-Open Patent Publication No. 2008-133448    Patent Document 6: Japanese Laid-Open Patent Publication No. 2009-7327    Patent Document 7: Japanese Laid-Open Patent Publication No. 2010-95643